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North Star Critter Spotlight: Bats!

Get to know a uniquely diverse order of mammals a little better as we shine this week’s North Star Critter Spotlight on Minnesota’s bats! Learn why four Minnesota bat species are of special concern in the state and what you can do to help combat a devastating bat disease sweeping North America.

Meet Minnesota Bats

Bats are members of the mammalian order Chiroptera (from the Greek for “hand-wing”), which is also split into the sub-orders Megachiroptera (megabats) and Microchiroptera (microbats). Megabats are also known as old world fruit bats or flying foxes, and with the exception of one species do not have the echolocation abilities characteristic of the microbats. Bats are the only mammals capable of true, sustained flight.

Seven bat species live in Minnesota, all from the family Vespertilionidae—the vesper or evening bats (the Latin word for bat, vespertilio, comes from the Latin for “evening”). Over 300 species of vesper bats are found around the world, on every continent except Antarctica.

Three of our Minnesota vesper bats migrate during the winter while the other four remain in the state to hibernate (it is these hibernating species that are of special concern in the state, as discussed in the Minnesota Status section below). These four hibernating Minnesota bats are:

Eptesicus fuscus, the big brown bat;

Up close and personal with Eptesicus fuscus (aka Big Brown Bat.) Did you know the latin name means: Dark house-flier? photo: cotinis

Vesper bats reproduce via delayed fertilization, meaning they mate in the fall and embryo implantation occurs in the spring after winter hibernation.

Minnesota’s seven vesper bats are all insectivorous (insect-eating) species that consume many of our insect pests. They provide useful service to Minnesota agriculture by reducing pesticide use and crop damage and helping to pollinate plants and disperse seeds.

Did You Know?

With over 1100 species, bats represent one-fifth of the world’s mammal species!

The world’s largest bat is the flying fox, which can have a wingspan up to six feet wide.

The world’s smallest bat (and arguably the world’s smallest mammal) is Kitti’s hog-nosed bat of Thailand (also known as the bumblebee bat), which is about 1.1 to 1.3 inches in length and weighs less than an ounce!

A single bat can live over 20 years, but bat populations are highly vulnerable because of their slow birth rate of usually just one baby (pup) per year.

Mother bats can find their pups among thousands or even millions of other bats according to their unique voices and scents.

Echolocationallows bats to hunt at night when fewer fellow predators are able to, making for less competition for prey. Using their echolocation calls, bats can determine where an object is, how big it is, and what direction it is moving—all in complete darkness!

Bat waste (guano) is highly rich in nutrients and is used by humans to fertilize crops.

Bat diets vary from species to species—many are insectivorous like our Minnesota bats, but other species eat fruit, nectar, or blood. There are even carnivorous bats that eat fish, frogs, lizards, birds, or other bats!

There are only three species of vampire bats that feed on blood in the world (and none of them live in the U.S.). There’s no real reason to be scared of these fellas. In fact, the anticoagulants found in their saliva that inhibit blood clotting when lapping up the blood of their prey are currently being used in medical research to help increase blood flow in stroke patients.

Bats really are fantastic insect-eaters. In the summertime, a nursing female bat can consume as much as its full body weight in insects each night, and the little brown bat (our Minnesota friend Myotis lucifugus) can catch and eat up to 1200 mosquitoes in one hour!

The Minnesota Department of Natural Resources classifies the four hibernating species of Minnesota bats mentioned above as species of special concern. Because they hibernate during the winter, they are all vulnerable to the devastating White-nose Syndrome currently threatening bats in North America.

White-nose Syndrome (WNS) was first observed in a cave in New York during the winter of 2006–07 as has since spread westward to 22 states and 5 Canadian provinces and killed 6 million bats. The syndrome is caused by a fungus (Pseudogymnoascus destructans)that thrives in the cold, humid conditions of caves and mines where bats hibernate (called hibernacula). The fungus can remain in cave after all bats have died and may be inadvertently carried to unaffected caves by humans or other animals.

There have not been any confirmed cases of White-nose Syndrome in Minnesota yet, but the fungus responsible for WNS has made it to our state, and the four hibernating Minnesota bats vulnerable to the fungus have been affected by WNS in other states.

The White-nose Syndrome fungus does not grow on bats during warm weather months. Observable signs of WNS during the winter include:

White fungus on a bat’s muzzle or other body parts such as the wings or tail;

Bats being outside and active during the day in below freezing temperatures;

Dead or dying bats outside.

State and local organizations, researchers, and federal, tribal, and non-governmental agencies are racing to learn more about White-nose Syndrome and stop its spread, lead in our state by the Minnesota DNR. You can help combat WNS by:

Reporting bats you find that are dead, dying, or showing signs of WNS. File a Bat Observation Report or contact the MNDNR’s Minnesota Biological Survey by emailing mbs.report@state.mn.us or calling 1-888-345-1730 to report such cases.

Not disturbing hibernating bats. Stay out of caves and mines where bats are hibernating. Respect cave closures and gates.

Preventing the spread of WNS. If you do enter caves or mines, follow proper decontamination procedures to clean your clothing and gear.

Helping bats survive. Enhance natural bat habitats around your home by minimizing outdoor lighting, retaining large trees, and protecting streams and wetlands. Provide a safe place for bats by setting up a bat house.

Being nice to bats. Exclude or remove unwanted bats without harming them and never during the young-raising season from May to August. Bats are remarkable yet vulnerable creatures and we would be worse off without them!

Sara C Swenson is a recent graduate from the University of Minnesota Twin Cities with a B.S. in Environmental Sciences, Policy, and Management (concentrated in Environmental Education and Communication) and a minor in Spanish. She has studied biology and conservation in the Galápagos Islands and the effects of tourism on coral reef ecosystems in Belize, is well-versed in Minnesota’s Environmental Review process, and has a longstanding interest in environmental policy and communication.